[libunwind] r292723 - X86: swap EBP, ESP on !APPLE

[Hans Wennborg via cfe-commits]

r293298.

Thanks,
Hans

On Thu, Jan 26, 2017 at 6:38 PM, Saleem Abdulrasool
<compnerd at compnerd.org> wrote:
> I think that this is safe enough and does make libunwind work on x86 Linux,
> so lets go for it.
>
> On Thu, Jan 26, 2017 at 10:10 AM, Hans Wennborg <hans at chromium.org> wrote:
>>
>> Michał suggested on the PR that this should be merged to the release
>> branch.
>>
>> Saleem, what do you think?
>>
>> On Sat, Jan 21, 2017 at 8:22 AM, Saleem Abdulrasool via cfe-commits
>> <cfe-commits at lists.llvm.org> wrote:
>> > Author: compnerd
>> > Date: Sat Jan 21 10:22:59 2017
>> > New Revision: 292723
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=292723&view=rev
>> > Log:
>> > X86: swap EBP, ESP on !APPLE
>> >
>> > Restore the `libunwind.h` enumeration values back to the inverted
>> > values.  This diverges from the DWARF definition of the register values.
>> > However, this allows our header to be compatible with other unwind
>> > implementations (e.g. HP, GNU Savannah, GCC).
>> >
>> > The register IDs are only swapped in the header and need to be unswapped
>> > when accessing the unwind register file.  The flipped EBP and ESP only
>> > applies on non-Apple x86 targets.
>> >
>> > When optimizations were enabled, EBP and ESP would no longer be
>> > equivalent.  As a result, the incorrect access on Linux would manifest
>> > as a failure to unwind the stack.  We can now unwind the stack with and
>> > without FPO on Linux x86.
>> >
>> > Resolves PR30879!
>> >
>> > Modified:
>> >     libunwind/trunk/include/libunwind.h
>> >     libunwind/trunk/src/Registers.hpp
>> >
>> > Modified: libunwind/trunk/include/libunwind.h
>> > URL:
>> > http://llvm.org/viewvc/llvm-project/libunwind/trunk/include/libunwind.h?rev=292723&r1=292722&r2=292723&view=diff
>> >
>> > ==============================================================================
>> > --- libunwind/trunk/include/libunwind.h (original)
>> > +++ libunwind/trunk/include/libunwind.h Sat Jan 21 10:22:59 2017
>> > @@ -165,13 +165,8 @@ enum {
>> >    UNW_X86_ECX = 1,
>> >    UNW_X86_EDX = 2,
>> >    UNW_X86_EBX = 3,
>> > -#if defined(__CloudABI__) || defined(__FreeBSD__)
>> > -  UNW_X86_ESP = 4,
>> > -  UNW_X86_EBP = 5,
>> > -#else
>> >    UNW_X86_EBP = 4,
>> >    UNW_X86_ESP = 5,
>> > -#endif
>> >    UNW_X86_ESI = 6,
>> >    UNW_X86_EDI = 7
>> >  };
>> >
>> > Modified: libunwind/trunk/src/Registers.hpp
>> > URL:
>> > http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/Registers.hpp?rev=292723&r1=292722&r2=292723&view=diff
>> >
>> > ==============================================================================
>> > --- libunwind/trunk/src/Registers.hpp (original)
>> > +++ libunwind/trunk/src/Registers.hpp Sat Jan 21 10:22:59 2017
>> > @@ -122,9 +122,17 @@ inline uint32_t Registers_x86::getRegist
>> >      return _registers.__edx;
>> >    case UNW_X86_EBX:
>> >      return _registers.__ebx;
>> > +#if !defined(__APPLE__)
>> > +  case UNW_X86_ESP:
>> > +#else
>> >    case UNW_X86_EBP:
>> > +#endif
>> >      return _registers.__ebp;
>> > +#if !defined(__APPLE__)
>> > +  case UNW_X86_EBP:
>> > +#else
>> >    case UNW_X86_ESP:
>> > +#endif
>> >      return _registers.__esp;
>> >    case UNW_X86_ESI:
>> >      return _registers.__esi;
>> > @@ -154,10 +162,18 @@ inline void Registers_x86::setRegister(i
>> >    case UNW_X86_EBX:
>> >      _registers.__ebx = value;
>> >      return;
>> > +#if !defined(__APPLE__)
>> > +  case UNW_X86_ESP:
>> > +#else
>> >    case UNW_X86_EBP:
>> > +#endif
>> >      _registers.__ebp = value;
>> >      return;
>> > +#if !defined(__APPLE__)
>> > +  case UNW_X86_EBP:
>> > +#else
>> >    case UNW_X86_ESP:
>> > +#endif
>> >      _registers.__esp = value;
>> >      return;
>> >    case UNW_X86_ESI:
>> >
>> >
>> > _______________________________________________
>> > cfe-commits mailing list
>> > cfe-commits at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>
>
>
>
> --
> Saleem Abdulrasool
> compnerd (at) compnerd (dot) org